Guys, at least give the kid the benefit of the doubt that he's telling the truth, until you have some evidence to the contrary. There's no need to belittle someone when you can just answer his question.
So, OP, your friend should be aware there is zero tolerance for drugs in the Coast Guard, and if he has taken them recently, there's a high probability he will not pass a drug test. He will be sent home if that's the case.
Hopefully he puts that behind him and moves on. I find it difficult to believe that someone intent on going to the Coast Guard Adademy would practice behaviors contrary to its stated mission. He probably needs to rethink his course in life.
And , OP, learn from his mistakes and make better choices.